import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		long v = Integer.parseInt(sa[0]);
		long t = Integer.parseInt(sa[1]);
		long p = Integer.parseInt(sa[2]);
		br.close();

		long val1 = v + v * p;
		long val2 = (val1 + t - 2) / (t - 1);
		System.out.println(val1 + val2);
	}
}